Abstract: A novel method of diagnosis of atherosclerosis comprises comparing the migration of endothelial cells or of cells of endothelium-like morphology in vitro, in the presence of serum from the person being examined, with the migration of identical cells in the presence of serum from healthy persons or of other standard sera, and interpreting a reduced migration in the presence of serum of the person being examined as being an indication of the possible existance of atherosclerosis in this person. The cell migration is measured for example on monolayer cell cultures of pig aorta endothelial cells or of Balb/c 3T3-A31 cells, in which cultures a portion of the cellular layer has been removed. An outfit for carrying out the method contains the materials and devices necessary for the purpose.